HIV-1 viral protein R causes peripheral nervous system injury associated with in vivo neuropathic pain

Painful peripheral neuropathy has become the principal neurological disorder in HIV/AIDS patients. Herein, we investigated the effects of a cytotoxic HIV-1 accessory protein, viral protein R (Vpr), on the peripheral nervous system (PNS). Host and viral gene expression was investigated in peripheral nerves from HIV-infected individuals and in HIV-infected human dorsal root ganglion (DRG) cultures by RT-PCR and immunocytochemistry. Cytosolic calcium ([Ca2+]) fluxes and neuronal membrane responses were analyzed in cultured DRGs. Neurobehavioral responses and cytokine levels were assessed in a transgenic mouse model in which the vpr transgene was expressed in an immunodeficient background (vpr/RAG1(-/-)). Vpr transcripts and proteins were detected in peripheral nerves and DRGs from HIV-infected patients. Exposure of rat or human cultured DRG neurons to Vpr rapidly increased [Ca2+] and action potential frequency while increasing input resistance. HIV infection of human DRG cultures caused neurite retraction (P<0.05), accompanied by induction of interferon-alpha (IFN-alpha) transcripts (P<0.05). vpr/RAG1(-/-) mice expressed Vpr together with increased IFN-alpha (P<0.05) in the PNS and also exhibited mechanical allodynia, unlike their vpr/RAG1(-/-) littermates (P<0.05). Herein, Vpr caused DRG neuronal damage, likely through cytosolic calcium activation and cytokine perturbation, highlighting Vpr's contribution to HIV-associated peripheral neuropathy and ensuing neuropathic pain.-Acharjee, S., Noorbakhsh, S., Stemkowski, P. L., Olechowski, C., Cohen, E. A., Ballanyi, K., Kerr, B., Pardo, C., Smith, P. A., Power, C. HIV-1 viral protein R causes peripheral nervous system injury associated with in vivo neuropathic pain. FASEB J. 24, 4343-4353 (2010). www.fasebj.org